Conventionally, as illustrated in FIG. 1(a), it has been proposed to provide a radial pneumatic tire for agricultural vehicles with lugs 92, on a tread surface 91, extending in a designated tire rotation direction from a tread edge TE towards the tread width direction inner side, the lugs 92 being arranged alternately in the tread circumferential direction in tread width direction halves divided by the tire equatorial plane CL (for example, see JP 2006-273052 A (PTL 1)). As illustrated in FIG. 1(b), in a tire circumferential direction cross-section, the lugs 92 have a shape that protrudes outward in the tire radial direction, with a wall 92b at the trailing edge side being steeper than a wall 92a at the leading edge side. In such a tire, the traction performance is ensured by the lugs 92 scratching soil, in agricultural fields and the like, when being driven. Furthermore, low-compaction lugs 92 are used so as not to damage the agricultural fields.
However, the environment of use of agricultural vehicles, such as tractors, is becoming faster, as seen by changes to standards in Europe and the USA. As a result, since the frequency of driving on public roads is increasing, there is a demand for measures to address problems of vibration due to increased speed. Therefore, one method of reducing the energy input from the road surface is a tendency to use the pattern illustrated in FIG. 2, in which the lugs 92 are disposed on the tread surface 91 so that when a first lug 92 in one of the tread width direction halves is projected in the tread circumferential direction, the first lug 92 overlaps a second lug 92 in the other tread width direction half near the tire equatorial plane CL. In such a pattern, the interval in the tread circumferential direction between lugs becomes narrow near the tire equatorial plane CL, thereby reducing the vibration input when driving at high speed.